Experimental vs. Numerical Computation of Acoustic Analyses on the Thickness Influence of the Multilayer Panel
Round 1
Reviewer 1 Report
The paper presents the mathematical modelling to calculate the acoustic impedance and absorption coefficient of a multi-layer material.
The method uses established model and it is not something new. However, it can be a reference for readers working with similar type of sound absorber.
My main criticism:
The absorption coefficient of the proposed multi layer is low (below 0.5) when the perforated sheet is applied on the front surface. Since the model has good agreement with experiment, the model can be used to simulate for other parameters (especially the perforation ratio or hole diameter of the perforated sheet) to improve the absorption coefficient. A thorough discussion must be provided.
In this way, the paper will have an added value for the readers, instead of just discussing the existing methods which can be found in other literatures.
Author Response
The authors want to address thanks for all the comments of the reviewer that contributed and added value to the research.
Response
“It was added the predictions for a porosity ratio in the range of 10%-70%, highlighted in figures 9-10. In this way, the new method PSAC-TMM has a great advantage because it predicts the sound absorption not only in the low range.”
Reviewer 2 Report
This work has studied the acoustic properties of multilayer panel by both experimental and numerical computation. A revision is necessary before the possible acceptance.
(1) In the introduction, this manuscript has described the studies of various models and methods. What is the highlights of this work compared with reported literatures ? Is it just a repetition of reported work ?
(2) How the acoustical and non-acoustical structural parameters were obtained ? The reliability of these data is important for computation process.
(3) In Figure 7 and 8, how to explain the difference between measured and predicted data ? Especially the measured absorption peak, which can not be predicted.
(4) It is suggested to supply the details of the numerical computation process. It is necessary for reviewer to evaluate the reliability of the results.
Author Response
The authors want to address thanks for all the comments of the reviewer that contributed and added value to the research.
Responses
- The work highlights a method of prediction PSAC-TMM that agrees with the experiments for a given porosity ratio. The method offers the possibility of analyzing the influence of the porosity ratio, a fact that was not yet studied in the literature.
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The method for the determination of acoustical characteristics was detailed and added in Appendix A. Some of the data are given by the producers(technical data information) and others were published in the literature. With all the respect, the authors mentioned in the paragraph Conclusion that in future work we will determine all the parameters in our Lab.
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Excepting the cases when the parameters may have slight differences from the data provided by the producers, in the revised manuscript was added a significant comment since the authors followed an analysis as detailed as possible (the analysis in both cases was performed on a linear regression on the frequency range 100-3200 Hz, with a step of 4 Hz, some small peaks appear that have considerable differences in the acoustic absorption values, but they are on very narrow domains)
“ For post-processing, the operation is possible to extract measured data to 1/1, 1/3, 1/12, or 1/24 octave”- lines 238-239.
When using octave representation, even very narrow ones such as 1/12 or 1/24 octaves, these peaks decrease so that the prediction values are very close to the experimental values. -
In the revised manuscript Table 3 was added, containing the parameters used by the new method PSAC-TMM.
Round 2
Reviewer 1 Report
The authors have revised the paper satisfactorily
Reviewer 2 Report
The revision has addressed all the comments. It is suggested to be possible publication.
